Polymer-Based Construction Blocks and Methods for Using Them

ABSTRACT

A prefabricated building block is used in the construction of structures. The block is composed of a polymer-based material, with a density of not more than 10 lbs. per cubic foot.

BACKGROUND

Construction of buildings has become moderately more efficient over the last several decades, but the associated costs continue to be considerable, both in labor and material.

Building materials in particular have generally experienced only evolutionary improvements over time. Strength, weight, thermal efficiency, durability, waste minimization, pest resistance, fire retardancy, microbe resistance and other competing material characteristics continue to present significant challenges when selecting building materials that are cost-effective, resilient, and safe.

Even as the accessibility and quality of materials improve, however, the cost of labor continues to climb. Modern construction techniques often require specialized knowledge and expertise, which can drive up the overall cost of the construction.

Many attempts have been made to streamline construction and reduce its costs, but none have been successful at significantly changing the long-used, expensive construction techniques still generally relied upon throughout the world. Information relevant to such attempts can be found in U.S. Pat. No. 3,305,982, No. 3,292,331, No. 7,694,485, No. 4,891,925, No. 7,007,436, and No. 6,648,715. Each one of these references, however, suffers from one or more of the following disadvantages: high building material cost, heavy building material weight (which can increase the cost of transportation and labor, if not the cost of the material itself), low durability, difficulty of construction/assembly (including, for example, the requirement of specialized equipment or expertise), length of time required for construction/assembly, or one or more poor building material characteristics (flame retardance, pest resistance, microbe resistance, UV resilience, thermal efficiency, etc.).

SUMMARY

The present invention is directed to a prefabricated interlocking construction block, structures composed of such blocks, and related methods of construction that overcome one or more of the disadvantages described above. A building constructed with features of the present invention comprises a plurality of prefabricated interlocking blocks (PFIBs) coupled together to form a structure. In one embodiment, the PFIBs are composed of a material comprising polyvinyl chloride and have a density of less than 10 lbs. per cubic foot.

A method of construction in accordance with the present invention comprises assembling PFIBs to form at least a portion of a wall. In one embodiment, the PFIBs are comprised of at least 20% polyvinyl chloride by weight.

A prefabricated interlocking block with features of the present invention is composed of a material comprising polyvinyl chloride and has an approximately rectangular cuboid shape. The interior of the block is substantially hollow, and the block has a density of less than 10 lbs. per cubic foot.

In one embodiment, the PFIBs are comprised of at least 6% barium sulfate by weight.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the embodiments of the present disclosure will become more apparent from the detailed description set forth below when taken in conjunction with the drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the disclosure and not to limit the scope of what is claimed.

FIG. 1A is a rendering of a PFIB according to an embodiment.

FIG. 1B is a cut-away side view of the PFIB shown in FIG. 1A.

FIG. 1C is a top view of the PFIB shown in FIG. 1A.

FIG. 2A is a rendering of a PFIB with open lateral faces according to an embodiment.

FIG. 2B is a side view of the PFIB shown in FIG. 2A.

FIG. 3A is a rendering of an extended PFIB according to an embodiment.

FIG. 3B is a side view of the PFIB shown in FIG. 3A.

FIG. 4 is a rendering of an assembly of PFIBs according to an embodiment.

FIG. 5 is a rendering of a wall composed of PFIBs according to an embodiment.

FIG. 6 is a rendering of a wall composed of PFIBs according to another embodiment.

FIG. 7 is a rendering of a PFIB cap according to an embodiment.

FIG. 8 is a rendering of a PFIB plug according to an embodiment.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are set forth to provide a full understanding of the present disclosure. It will be apparent to one of ordinary skill in the art, however, that the various embodiments disclosed may be practiced without some of these specific details. In other instances, well-known structures and techniques have not been shown in detail to avoid unnecessarily obscuring the various embodiments.

Prefabricated interlocking blocks (PFIBs) disclosed herein are particularly configured for use as building blocks in the construction of various above-ground and in-ground structures, including but not limited to residential and commercial buildings, sheds, out buildings, greenhouses, playhouses, fences, signs, basements, retaining walls, landscaping effects, septic tanks, water tanks, pools, swimming pools, and water ways. The PFIBs are low-density, high-strength blocks designed for ease of assembly. They may be assembled in courses such as bricks, but are self-interlocking and do not typically require mortar or glue. Such PFIBs may be fabricated in multiple sizes and with various features.

FIG. 1A is a diagram of a prefabricated interlocking block (PFIB) 100 according to an embodiment of the present invention. Being approximately a rectangular cuboid in shape, PFIB 100 comprises six faces: 110, 120, 130, 140, 150, and 160. Faces 110 and 160 sit on opposite sides of PFIB 100 and have openings that expose a channel through the cavity of PFIB 100. PFIB 100 is substantially hollow in order to reduce its weight and cost and to enable the incorporation of building-related materials into the interior of an assembly of multiple PFIBs. Those skilled in the art will understand that PFIB 100 can be any three dimensional shape, and that a rectangular cuboid is just one example. For example, shapes such as cube, sphere, ellipsoid, cylinder, cone, triangular prism, hexagonal prism, triangular-based pyramid, square-based pyramid, hexagonal pyramid, tetrahedron, octahedron, dodecahedron, icosahedron, and even irregular shapes could be used for PFIB 100. PFIBs may also be fabricated with arced shapes to facilitate the construction of structures with arches.

The portions of PFIB 100 at faces 110 and 160 also comprise interlocking features designed to connect PFIB 100 to other PFIBs (or to mounts with similar interlocking features). Face 110 comprises a protruding feature 118, while face 160 comprises a recessed feature 116. Protruding feature 118 has dimensions such that it fits snugly within the corresponding recessed feature of another PFIB. Protruding feature 118 preferably also has dimensions which, when taken in combination with the plasticity and other material properties of PFIB 100, should enable protruding feature 118 of PFIB 100 to be fully inserted into the recessed feature of another PFIB with no more force than a single person may exert on the blocks (i.e., without the need for resort to electromechanical devices).

Protruding feature 118 and recessed feature 116 could be said to form a male/female physical interconnection pair. Those skilled in the art will understand that many interconnection methods, including tongue and groove connections, can be used to connect adjacent PFIBs in other embodiments. Such interconnection methods preferably require either some force or a particular motion for the connection between PFIBs to be disturbed, but less durable interconnection methods may be used as well (e.g., simple grooves in the tops and bottoms of the PFIBs that facilitate proper alignment of the PFIBs), especially if adhesive or another bonding technique (such as ultrasonic bonding) will be used to further strengthen the connection between the blocks.

As shown in FIG. 1A, the portions of PFIB 100 at faces 120, 130, 140, and 150 comprise solid and substantially flat, unbroken surfaces. The thickness of the sidewalls comprising faces 120, 130, 140, and 150 may be adjusted based on the planned use of PFIB 100. In one embodiment, for example, the thickness can be 5/32″. In other embodiments, for example, the thickness can be between 0.1″ to 0.3″. Thicker sidewalls enhance the strength of the PFIB, but may also increase the costs of materials, transport, assembly, and finishing.

For ease of construction, PFIB 100 preferably has a depth that approximates the thickness of walls built according to traditional construction techniques, such as wood-framed buildings based on 2×4 boards. As such, in one embodiment, PFIB 100 can be approximately 4.5″ wide, 7″ tall, and 4.5″ deep.

FIG. 1B is a diagram of PFIB 100 in cut-away side view.

FIG. 1C is a diagram of PFIB 100 in top view.

FIG. 2A is a diagram of PFIB 200 according to another embodiment. PFIB 200 has dimensions similar to those of PFIB 100, but differs in that two of its lateral faces, 220 and 240, comprise openings exposing the hollow interior (or cavity) of PFIB 200. Such openings can accommodate building-related materials such as laterally-run cables, plumbing, or other things desired to be placed within a wall.

FIG. 2B is a diagram of PFIB 200 in side view.

FIG. 3A is a diagram of a larger PFIB 300. Although small PFIBs are desirable to enable construction of walls according to more varied dimensional specifications, larger PFIBs can also be used to speed assembly of a wall and to enhance its structural integrity. For example, PFIB 300 can be approximately 36″ wide, 7″ tall, and 4.5″ deep. It will be appreciated that PFIBs may be fabricated with any desired widths and heights, though it is preferable that the dimensions be in multiples of a specified smallest PFIB unit size to ensure the blocks are compatible with each other. For example, if the smallest PFIB has a width of 4.5″, larger blocks may have widths of 2×(9″), 3×(13.5″), 4×(18″) and so on.

FIG. 3B is a diagram of PFIB 300 in side view.

PFIBs may be assembled into many desired structures, including residential or commercial buildings, freestanding walls, playhouses, etc. The simplicity of building with PFIBs is one of their advantages, since PFIB assembly is typically faster than traditional building techniques and may not require skilled labor. In general, PFIBs are laid in successive courses similar to bricks, but without the need for mortar. Because PFIBs are designed to interlock with each other when pressure is applied, they are naturally self-leveling and self-aligning. The PFIBs should fit snugly together, which further facilitates rapid assembly. Assembly of PFIBs is thus nearly as simple as building structures using toys such as LEGOs, but on a much larger scale.

There are several ways in which a PFIB-based structure can be secured to the ground or an existing foundation. If no foundation or footing yet exists, PFIBs may be used as forms for concrete footings. In this case, trenches are dug where the footings should be laid (e.g., where externally-facing or load-bearing walls will be built). Next, PFIBs are laid in the trenches. As one example, one to three rows of PFIBs can be laid side by side to ensure the footings are sufficiently strong. Next, a second course of PFIBs can be placed on and interconnected with the first course. This second course can help to ensure that the PFIBs are aligned and level with each other. The rows of PFIBs that are situated directly below the anticipated walls can be located over any plumbing intended to be run through the walls, with the plumbing exposed through the tops of the PFIBs. Rebar can be placed within the PFIB assembly to enhance the strength of the resulting structure. Further, concrete can be poured into the cavities in the PFIBs, leaving the tops of the PFIBs with the interconnecting features exposed. J-bolts may be placed in the wet concrete to facilitate hurricane resistant building techniques, as described further below. The walls of the structure can then be built by simply laying successive courses of PFIBs on the exposed PFIB-based footings. It may be useful to cut off the top interlocking features of the concrete-filled PFIBs that are not used to directly interlock with other PFIBs (e.g., for walls built on top of them), rendering the tops of those exposed footings smoother and less prone to damage and/or interference with subsequent construction activities.

These PFIB-based footings have several advantages. Such footings eliminate the need for concrete forms. They also create naturally square footings due to the shape and interlocking features of the PFIBs. The resulting footings are also very strong—and the strength can be further enhanced by using additional rows of PFIBs and/or trenching deeper and filling more vertically-stacked PFIBs with concrete. This method also helps to ensure that building-related materials (such as plumbing) intended to be routed through the walls is in the correct location before the footings are finished (at which point adjustments are much more difficult).

Alternatively, two or more courses of PFIBs could be set 2 or more inches in concrete with traditional footings or a slab while the concrete is wet. The concrete can then cure around the base of the PFIBs, anchoring them to the ground.

A PFIB-based structure may also be built on an existing concrete slab. In one such method, masonry nails are nailed into the slab at regular intervals underneath where the first course of PFIBs is to be laid, with a portion of the nails (e.g., 0.25″) left protruding from the concrete. Two courses of PFIBs are then laid over the nails, and the cavities of the PFIBs are filled with enough concrete to secure the PFIBs to the nails and slab (typically 2″ or more). In some locations, it may be desirable or required to place a number of wedge anchors or “red heads” in the concrete before laying the PFIBs, which allows an entire PFIB assembly to be secured to the ground using the cabling method described below.

In some situations it may be possible or expedient to lay PFIBs on an existing concrete slab or base without modification to the slab or base. In those cases, it may be preferable to seal the initial course of the PFIBs to the foundation with a bonding agent to prevent leakage of water or other contaminants. Such a bonding agent may also be advantageous by enhancing the load-bearing capacity of the PFIB assembly by increasing the degree of physical contact between the first course of PFIBs and the concrete underneath them. One or more courses of PFIBs may be filled with a dense filler (such as concrete or sand) to better anchor the PFIB assembly.

When PFIBs are laid, courses preferably either are staggered or incorporate various lengths of PFIBs. Thus the courses can be designed to avoid having junctures (seams) between PFIBs line up between successive courses, which could weaken the integrity of the assembled PFIBs.

When used in the construction of a permanent building, it will often be desirable to make use of the cavities of the PFIBs to house structural supports, building infrastructure, or insulation for the building. In some circumstances, it may be necessary or advisable to increase the strength (especially the compression strength) of an assembly of PFIBs, such as when multi-story buildings are constructed. In such situations, wood or steel support beams may be run through the vertical channels formed by the interconnecting cavities of the assembly of PFIBs. The openings in the tops and bottoms of the PFIBs (as well as the openings in the lateral faces, in PFIBs with such openings) are thus preferably large enough to accommodate traditional wood or steel support beams. Such support beams may increase the weight-bearing capacity of the PFIBs. The number of beams used can be adjusted to meet the structural requirements of the building. The beams may be fastened to boards run horizontally across the top of a PFIB assembly (the top plate). Similarly, the top plate itself may be run horizontally through a channel in the top course of the PFIB assembly, rather than rest on top of the top course.

Similarly, the interconnecting cavities of an assembly of PFIBs can house building-related materials. PFIBs such as the one disclosed in FIG. 2A allow plumbing and wiring to be run horizontally through the assembly. By orienting adjacent PFIBs such that the lateral faces with openings face each other, a lateral (typically horizontal) channel can be created between the cavities of the PFIBs.

A number of PFIBs can be fabricated with integrated junction boxes designed for housing electrical components. PFIBs can also be fabricated with openings designed to accommodate (and, where appropriate, anchor) traditional outlet boxes, light switch boxes, clean-outs, gas lines, and water lines. Such PFIBs may be called “access PFIBs,” since they provide access to components that are ultimately housed inside the PFIB assembly.

In most circumstances, construction of a PFIB-based building will proceed, course by course, until the height is reached at which either: (1) electrical outlets, plumbing tie-ins, or other intra-wall access points are desired, or (2) wires, pipes, or other components are desired to be run horizontally. At that point, any access PFIBs available can be laid at the locations where access is required. Then the electrician or plumber will route the plumbing, wiring, etc., through the cavities of the PFIBs assembled thus far and, as appropriate, expose access to the unfinished wiring or plumbing through an opening in the PFIB assembly (either through a specially-designed access PFIB or an ordinary PFIB that has been modified after fabrication to permit such access).

Insulation may also be placed within the cavities of an assembly of PFIBs. PFIBs are especially adapted for blow foam or dry loose fiberglass insulation, which can be blown into the cavities of the assembled PFIBs once the assembly is complete. But other forms insulation may also be placed in PFIBs before or during assembly. Insulation also may be incorporated into some PFIBs as an additional step in the manufacture of the PFIBs, i.e., before the PFIBs are delivered to the construction site. The insulation may partially obstruct the channel created by the PFIB's hollow center and open faces, fully obstruct the channel, or not obstruct it at all, depending on the type of insulation used, the method of installing the insulation, and the balance of priorities for the structure being built.

FIG. 4 is a diagram of a partially-assembled wall 400 comprised of multiple PFIBs 410. Cap-type PFIBs 420 can be used on the top of the assembly to finish it and provide a flat surface. PFIBs 410 have a density much lower than traditional building materials. Under some circumstances it may be necessary or prudent to more tightly secure PFIBs 410 to the ground or foundation and thus enhance the durability of the assembled PFIBs. For example, in locations where strong winds or other extreme weather events are likely to arise, fastening PFIBs 410 to a foundation 430 may render the wall even more durable than buildings constructed with more dense building materials.

Such an example is shown in FIG. 5, which shows a fully-constructed PFIB-based wall 500. Support line 550 (such as a steel cable) can be secured to mounts 520 (such as J-bolts or wedge anchors) in the foundation 530 before assembly of wall 500, then looped through the channels in PFIBs 510. Top plates 570, such as 2×4s, can be placed within the top course of PFIBs of the assembled wall 500 (or, alternatively, on top of the assembled wall 500) and the support line 550 is secured to the top plate 570, such as through holes drilled through the top plate 570 or with a bolt 580. Support line 550 should be tightened such that it reliably holds PFIBs 510 to foundation 530 but does not compromise the integrity of PFIBs 510. Roof trusses may be connected to the top plate 570, and hurricane straps may be attached, especially where required by local building codes. Cap-type PFIBs 525 are used to finish the top of the wall 500. FIG. 6 depicts an embodiment of a wall 600 composed of PFIBs 610 in which roof trusses 670 are coupled to support line 650 via a clamp 680. Support line 650 is anchored to foundation 630 via J-bolt 620. In this embodiment, the support line 650 secures the roof trusses 670 to the foundation 630, with the PFIBs 610 secured between them.

As mentioned above, when additional strength, durability, or wall density is desired, PFIBs may be reinforced by support beams (such as wood or steel beams) run through the cavities in a PFIB assembly. In some situations, it may even be desirable to fill the cavities in a PFIB assembly with sand or concrete. Doing so would increase the strength and durability of the assembly, but would make any modification to the PFIBs or any components housed within the PFIBs very difficult or impossible. Also, filling a PFIB assembly with concrete would typically render the PFIBs non-reusable, whereas unmodified PFIBs are otherwise generally easy to disassemble and reuse.

The strength of a PFIB assembly may also be enhanced by placing an adhesive compound between adjacent PFIBs. The adhesive compound can be traditional PVC glue, for example. Connecting PFIBs together by adhesive may provide enough vertical wall strength to satisfy wind load requirements; after the wall is glued, hurricane straps could be fastened from trusses to boards run through the top course(s) of the PFIB assembly or to other anchors (e.g., in the ground or foundation).

Using adhesive compounds between PFIBs can also create a stronger seal and barrier between the opposite sides of a PFIB assembly. Alternatively, heat welding techniques (including ultrasonic welding) can be used to bond PFIBs permanently together and create water/air tight seals between them.

When PFIBs with openings on their lateral faces are used, horizontal beams, such as one or two 2″×6″ boards or steel studs, can be run horizontally through a PFIB assembly. Such horizontal beams can be used to create structural features and supports including floor joists, ceiling joists, headers, and door and window frames. Since PFIBs are preferably formed of a PVC composite, special PFIBs may be manufactured to simply receive and anchor glass for windows—a pre-assembled window in a vinyl frame would not be necessary. Traditional windows in pre-assembled frames are fully compatible with PFIBs, however, and may be nailed, screwed, glued, or otherwise secured to a PFIB assembly.

In addition to the access PFIBs specifically designed for accommodating electrical and plumbing components, unique PFIBs may be used for other purposes. PFIB caps may be created to finish off the top of a PFIB or PFIB assembly. Such caps would interlock with the top interlocking feature of the PFIB to be finished, creating a flat surface on the top of the PFIB. FIG. 7 is a diagram of an example PFIB cap 700.

A useful PFIB height is 7″, which corresponds to a typical stair step rise. When stairs are constructed with PFIBs, such PFIB caps may be used to create the top surface of the stairs. Such PFIB caps preferably have a greater thickness than the sidewalls of typical PFIBs, since they may support substantial forces orthogonal to their exposed surface (e.g., foot traffic). PFIB caps may also be created with overhangs, for use as stair tops or windowsills, for example.

FIG. 8 depicts an embodiment of a PFIB plug 800 designed to be coupled to the bottom of a PFIB such as depicted in FIG. 1A. In some applications, such plugs may be desirable to create a smooth surface and/or barrier on the bottom of the block (e.g., for temporary or movable structures).

Other specially-shaped PFIBs may also be formed to accommodate floor joists when a multi-story building is being constructed.

PFIB assemblies may be finished in any number of ways. PFIBs may be colored during fabrication, such that no finishing is necessary or desired. Alternatively, they can be painted. The exposed surfaces of PFIBs may also be lightly scored or textured during or after fabrication to enhance adhesion of paint. Seams between individual PFIBs can be caulked or filled with any other acceptable compound to create a substantially smooth surface for a PFIB assembly.

In some circumstances, it may be preferable for the exposed surfaces of a PFIB assembly not to be smooth. Smooth surfaces are more prone to show defects, for example, and may be less visually appealing in some settings. PFIBs may be molded during manufacture to create a non-uniform surface on the faces of the PFIB that will ultimately be exposed in the PFIB assembly. The surfaces may be contoured to resemble stone, brick, wood, or any other desired material.

PFIB assemblies may also be textured once assembled. A stucco-like substance may be applied using traditional techniques, including trowel, roller, or sprayer. (As with paint, adherence of the texture to the PFIB assembly may be enhanced by scoring or texturing an exposed surface of each relevant PFIB during or after fabrication.) Such finishing may not be functionally necessary, but can render the PFIBs more adapted to varied aesthetic preferences, since many colors, textures, and other surface effects could be used. A traditional textured drywall-like surface could easily be created with a sprayer, for example.

Alternatively, traditional drywall can be hung on PFIB assemblies. Shorter screws or nails may be used, due to the relative thinness of the PFIB sidewalls, but the drywall can otherwise be finished as in traditional construction methods. PFIBs preferably are formed of a polyvinyl chloride (PVC) composite and are fabricated by injection molding. PVC is strong, lightweight, fire retardant, relatively inexpensive, and is thus an effective material for construction. PVC with hardness in the range K 64-69 is preferable. Injection and extrusion molding facilitates mass production of PFIBs at acceptable tolerances to ensure the PFIBs reliably interlock with each other. PFIBs may also be formed by fused deposition modeling, stereolithography, digital light processing, selective laser sintering, selective laser melting, laminated object manufacturing, binder jetting, and 3D printing and other similar methods.

The composition of PFIBs may be adjusted depending on whether the blocks are intended for external or internal use. PFIBs used for exterior walls should be particularly resistant to sunlight (especially UV radiation) and heat, for example. A typical formulation for PFIBs intended to be exterior-facing is as follows (quantities being expressed as parts per hundred, by weight, of PVC): 100 Polyvinyl Chloride (K 64-69); 85 Barium Sulfate; 27 Chopped Strand Glass Fibers; 13 Ethylene Vinyl Acetate; 3.6 Epoxidized Linseed Oil; 2 Barium Cadmium Zinc; 1.1 Antimony Trioxide; 0.8 Mica-Based Pigment; 0.7 Stearyl Alcohol; 0.5 Octyl Tin Mercaptide; 0.5 Stearic Acid; 0.4 Rutile Titanium Dioxide. Some or all of the PVC may be recycled.

This composite is sufficiently strong and dense that it can be foamed during fabrication (with carbon dioxide or nitrogen, for example) to reduce its density—and the weight of the resulting PFIBs. The foaming process expands the composite by introducing small bubbles of gas. Preferably, the foaming process is used to reduce the density of the composite by 40-95%. PFIBs fabricated according to this process, this formula, and these dimensions should easily withstand more than 400 lbs. of weight, properly distributed.

Formulations for exterior-facing PFIBs may be adjusted based on costs and required material characteristics. The composition of exterior-facing PFIBs may thus fall within the following ranges: 100 Polyvinyl Chloride (K 64-69); 45-120 Barium Sulfate; 13-31 Chopped Strand Glass Fibers; 11-34 Ethylene Vinyl Acetate; 0.5-4.3 Epoxidized Linseed Oil; 1.3-3 Barium Cadmium Zinc; 0.3-3.3 Antimony Trioxide; 0-5 Mica-Based Pigment; 0.1-4 Octyl Tin Mercaptide; 0.3-1.8 Titanium Dioxide; 0.1-2 Stearyl Aclohol; 0.1-2 Stearic Acid.

The addition of barium sulfate offers several advantages, especially for externally-facing PFIBs. It is a fire retardant, it enhances the longevity of the composite, it increases the weight and density of the composite (and thus its durability), and it increases resistance to UV radiation.

Barium sulfate also greatly enhances the reflectivity of the composite. For externally-facing PFIBs, the reflectivity can improve the thermal efficiency of a PFIB-based structure by reducing the amount of heat absorbed from sunlight or other radiation, including thermal radiation. Structures built with such PFIBs can thus have reduced needs for cooling and insulation compared with traditional building materials. The PFIBs may also have greater longevity due to the reduction in thermal swings to which they are subjected.

A typical formulation for PFIBs intended for internal use is as follows: 100 Polyvinyl Chloride (K 64-69); 72 Novaculite; 36 Barium Sulfate; 27 Chopped Strand Glass Fibers; 19 Ethylene Vinyl Acetate; 1.9 Ammonium Laureth Sulfate; 1.5 Antimony trioxide; 1.0 UV Absorber (e.g., Hostavin 3330 DISP XP); 1.0 Stearyl Alcohol; 0.8 Stearic Acid; 0.4 Barium Cadmium Zinc; 0.18 Rutile Titanium Dioxide; 0.08 Octyl Tin Mercaptide.

As with the formulations for exterior-facing PFIBs, the formulations for interior-facing PFIBs may be adjusted based on costs and required material characteristics. The composition of interior-facing PFIBs may thus fall within the following ranges: 100 Polyvinyl Chloride (K 64-69); 15-85 Barium Sulfate; 5-85 Novaculite; 13-31 Chopped Strand Glass Fibers; 13-32 Ethylene Vinyl Acetate; 1.5-3.2 Ammonium Laureth Sulfate; 0.5-2.5 UV absorber; 0.3-2 Barium Cadmium Zinc; 0-4 Pigment; 1-3.8 Antimony Trioxide; 0.1-2 Stearyl Alcohol; 0.1-1.5 Stearic Acid; 0.1-01.2 Rutile Titanium Dioxide; 0-1.2 Octyl Tin Mercaptide.

The composites described above, when foamed during fabrication, can lead to extremely light yet strong building materials. The low density of the resulting PFIBs is one of their advantages, as the transport and assembly of low-density blocks is simpler and cheaper. Empty PFIBs thus fabricated will preferably have a density of less than 10 lbs. per cubic foot, and in most embodiments less than 4 lbs. per square foot. In certain applications requiring additional strength, the PFIBs may be fabricated with: (1) thicker walls, (2) more barium sulfate (or other dense materials), and/or (3less/no expansion via foaming. Each of those options would result in a stronger and denser PFIB, which could still be much lighter than traditional building materials, but heavier than the baseline PFIB formulation described herein. Compared with traditional building materials, however, even these relatively denser PFIBs would have advantages over traditional building techniques, as described above. 

What is claimed is:
 1. A pre-fabricated building block comprising: a frame having an approximately rectangular cuboid shape comprising six faces, the frame composed of a material comprising polyvinyl chloride; wherein the interior of the frame comprises a hollow space; wherein the density of the block is less than 10 lbs. per cubic foot; and wherein the block is configured to interconnect to another block.
 2. The block of claim 1, wherein the material of which the frame is composed further comprises at least 6% barium sulfate by weight.
 3. The block of claim 1, wherein the block has a density of less than 4 lbs. per cubic foot.
 4. The block of claim 1, wherein the material of which the frame is composed comprises at least 20% polyvinyl chloride by weight.
 5. The block of claim 1, wherein the block has a volume of at least 0.07 cubic feet.
 6. The block of claim 1, wherein the block further comprises: substantially uniform and uninterrupted sidewalls on at least two of the block faces; at least one block face comprising a male interlocking feature; at least one block face comprising a female interlocking feature; at least two block faces each comprising an opening covering at least 25% of the surface area of each of the at least two block faces.
 7. The block of claim 1, wherein the material of which the frame is composed further comprises a UV inhibitor.
 8. The block of claim 1, wherein the hollow space comprises at least 50% of the total volume occupied by the block.
 9. A polymer-based block for construction of walls or buildings, comprising: an interlocking feature; wherein the block has a density of less than 10 lbs. per cubic foot.
 10. The block of claim 9, wherein the block comprises at least one surface that is textured to be substantially rough.
 11. The block of claim 10, wherein the block is substantially in the shape of a rectangular cuboid, the block further comprising: a substantially flat surface opposite the face comprising the interlocking feature; wherein the block is configured to act as a plug or a cap when coupled to a second block having at least one open face.
 12. The block of claim 10, further comprising a receptacle for glass.
 13. The block of claim 10, further comprising a receptacle for a junction box.
 14. The block of claim 10, further comprising an integrated junction box.
 15. The block of claim 10, further comprising at least one curved surface; wherein the block forms an arch when coupled with one or more other blocks.
 16. The block of claim 10, wherein the block is composed of a material having reduced density due to foaming of its polymer-based material during fabrication.
 17. The block of claim 10, wherein the block is composed of a material comprising at least 20% polyvinyl chloride by weight.
 18. The block of claim 10, wherein the block is composed of a material comprising barium sulfate, novaculite, chopped strand glass fibers, ethylene vinyl acetate and ammonium laureth sulfate.
 19. A method of manufacturing a block for use as a structural component, comprising: foaming a material comprising at least 20% polyvinyl chloride; and forming the material into the shape of the desired block; wherein the block has a resulting density of less than 10 lbs. per cubic foot.
 20. The method of claim 19, wherein the block is formed via injection molding. 